Cognitive reserve and appraisal in multiple sclerosis

Abstract

Background

Cognitive appraisal processes underlying self-report affect the interpretation of patient-reported outcomes. These processes are relevant to resilience and adaptability, and may relate to how cognitive reserve protects against disability in multiple sclerosis (MS).

Objectives

To describe how passive and active indicators of cognitive reserve relate to QOL appraisal processes in MS.

Methods

Cross-sectional data (n=860) were drawn from the North American Research Committee on MS (NARCOMS) Registry, from whom additional survey data were collected. Cognitive reserve was measured using the Stern and Sole-Padulles measures. Using the quality of life appraisal profile (QOLAP), we assessed how MS patients conceptualize their experiences and how that impacts how they report their quality of life. Multivariate analysis of variance was used to compare groups within sets of appraisal parameters, and t-tests or chi-square tests were used to compare mean item responses within appraisal parameters for continuous or dichotomous variables, respectively.

Results

People high in passive or active reserve report different conceptualizations of QOL, different types of goals, and considering different types of experiences and standards of comparison in responding to QOL questionnaires, as compared to low-reserve individuals. Although item response patterns were slightly different between passive and active indicators, they generally reflect a tendency in high-reserve individuals to emphasize the positive, focus on aspects of their life that are more controllable, and less based in fantasy.

Conclusions

MS patients high in cognitive reserve differ in their cognitive appraisals from their low reserve counterparts. These appraisal metrics may predict disease course and other important clinical outcomes in MS patients.

Introduction

Cognitive reserve is an intriguing construct that has been studied in neurologic diseases, brain injury, and aging (Stern, 2007). Originally motivated by the repeated observation of poor correspondence between brain pathology and clinical presentation(Stern, 2007), the concept of cognitive reserve has broad implications for understanding resilience in the face of neurological disease. In the context of multiple sclerosis (MS), cognitive reserve may buffer patients against the long-term cognitive effects of the disease(Arnett, 2010) and possibly even for the transition from relapsing-remitting to progressive disease course.

Cognitive reserve theory (Stern, 2007) posits that there are two components of reserve: passive and active. Whereas passive reserve reflects past and premorbid indicators of brain reserve (e.g., IQ, educational and occupational attainment, childhood enrichment activities, etc.), active reserve reflects current enriching activities that keep the brain active and fit (e.g., stimulating leisure and cultural activities, exercise, etc.). Recent work by our group has documented consistent and substantial relationships between both reserve components and patient-reported outcomes (Schwartz et al., in press). Individuals with high passive and/or active reserve appear to be healthier and experience higher levels of well-being (Schwartz et al., in press). From the literature on cognitive reserve, Richards and Deary (2005) have proposed a Life Course Model of Cognitive Reserve that posits four types of influences on the clinical expression of disease. Pre-morbid cognitive ability and other influencing factors (genes, education, lifestyle behaviors) indirectly influence disease expression and central nervous system lesions; other factors (e.g., cultural norms) directly influence disease progression. The Richards and Deary model provides a useful theoretical starting point for thinking about cognitive reserve. It accommodates important complexities. Later exposure and behaviors are linked to early determinants (i.e., exposure and behaviors), and patterns of risk and protection are likely to accumulate over the life course (Richards et al., 2007, Kuh and Ben-Shlomo, 1997, Kuh and Cooper, 1992).

There is a growing body of research that suggests that the QOL appraisal processes underlying self-report affect the interpretation of patient-reported outcomes across a range of medical conditions. Cognitive appraisal processes underlie patient response to surveys or questionnaires (Tourangeau et al., 2000). These mental steps that people go through when they answer questions on a survey have implications for accurately interpreting survey responses (Tourangeau et al., 2000). Indeed, part of questionnaire development involves cognitive interviewing to understand what thoughts and feelings are evoked by specific questions to ensure that they are those intended (Willis, 2005). Even when developers follow the current doctrine about best practices for questionnaire design (NIH, 1996), however, other patient factors come into play that yield clinically relevant differences in the underlying appraisal processes. There is, for example, evidence that better adaptation to chronic illness is characterized by using specific patterns of QOL appraisal processes. For example, HIV/AIDS patients who reported better mental health than would be expected based on overt health status used appraisal strategies such as avoiding to think about things that are disappointing, worrisome, or difficult (Bobinski and Lipinski, 2009). The cognitive processes underlying patient response to patient-reported outcome measures have also been found to change over time in cancer patients, and to be affected by treatment side-effects (Taminiau-Bloem et al., 2010). These findings suggest that QOL appraisal processes are relevant to resilience and adaptability. It is possible that such changes in appraisal may be indicative of cognitive flexibility, which may be adaptive in some circumstances (Schwartz et al., 1998) but maladaptive in others (Schwartz and Daltroy, 1999).

The theoretical model underlying our work is an integration of a useful theory from the cognitive reserve research arena – the abovementioned Richards and Deary cognitive reserve model (Richards and Deary, 2005) – and the appraisal and response shift theory of Sprangers and Schwartz (1999)) and Rapkin and Schwartz (2004)). The response shift model posits that a health (see Fig. 1). Response shift theory provides a useful way to think about how cognitive reserve may impact clinical presentation in MS. The response shift theoretical model (Rapkin and Schwartz, 2004) posits that a health state change (catalyst) causes an individual to utilize cognitive, behavioral, and emotion-focused coping strategies (mechanisms), and that stable characteristics of the individual (antecedents) determine the selection of these strategies. The Richards and Deary conceptualization of cognitive reserve fits into antecedents in our model. This interaction of antecedents and mechanisms yields appraisal processes, which influence perceived QOL. There are four specific appraisal processes of note in this model: (1) Frame of Reference: What life domains are relevant to an individual’s QOL mean?; (2) Sampling of Experience: What experiences does the individual consider pertinent within these domains?; (3) Standards of Comparison: What points of reference does the individual use to evaluate these experiences?; and (4) Combinatory Algorithm: What is the relative importance attributed to these different evaluations in forming an overall QOL rating?. These appraisal processes determine perceived QOL, both immediately and over time as this iterative process repeats itself in a feedback loop. Appraisal measures have been used to understand instances when ratings of QOL differ appreciably from expected values—for example, when an individual’s QOL ratings remain stable or even improve despite worsening health status. Changes in appraisal that explain discrepancies between expected and observed ratings of QOL are referred to as “response shifts” (Rapkin and Schwartz, 2004). Changes in appraisal can either affect QOL ratings directly (Direct Response Shift) or can affect QOL ratings by attenuating the impact of “catalysts” such as worsening health status (Moderated Response Shift).

The purpose of the present work is to investigate how passive and active cognitive reserve influence the appraisal process. It is expected that appraisal processes will differ in high versus low cognitive-reserve groups, and that these differences will be distinct for passive versus active reserve. Note that in our theoretical model, passive cognitive reserve would be considered a background or “antecedent” construct, while active cognitive reserve would function as a “mechanism” that directly determines current appraisal. Thus, these two components may not be identical in the appraisal processes they evoke. For example, active and passive reserve could affect appraisal independently, active reserve could mediate the influence of passive reserve, or the two aspects of reserve could interact in a synergistic manner.